Mind and Body

Living Kidney Donor Chains Facilitate More Matches

In 2006, one healthy young man stepped forward, willing to give one of his kidneys to a complete stranger. Two years later, 10 people had received new kidneys from that one remarkable altruistic act.

As a result of this donation, the first non-simultaneous, extended altruistic-donor (NEAD) chain was created.

The woman who received the altruistic donor's kidney had a family member (her husband) who was willing to donate, but could not donate to his wife.

So, the husband gave his kidney to a young woman whose mother was also willing to donate, but did not match, and so on, and so on, until 10 successful transplants had occurred.

The final donor in the chain is still waiting for a good match to someone in need of a kidney.

Computer Matching Extends Reach

If all of this sounds complex and difficult to coordinate, it is. But, fortunately the physicians involved now have sophisticated computer programs to help them match possible recipients to willing donors.

"We've now transplanted 19 people through NEAD chains," says study author Dr. Michael A. Rees, director of renal transplantation at the University of Toledo Medical Center. "We've started six NEAD chains. The first one is 10 in length, the second is five," he says, adding that he hopes each chain never ends.

Details of the first NEAD chain are published in the New England Journal of Medicine (NEJM).

Nearly 80,000 people are waiting on the transplant list for a new kidney, according to the Organ Procurement and Transplantation Network.

Many of these people have a friend or family member who is willing to donate a kidney but cannot because of a mismatch or other problem.

Unmatched Donors Have Access To Others

People can find themselves unable to donate to a loved one if their blood type does not match or if they have developed certain antibodies, which can occur through blood transfusions or in pregnancy.

But instead of turning those willing donors away, doctors came up with the idea of paired donation. In paired donation, two transplant recipients essentially swap their donors to make a good donor-recipient match.

These operations are done at the same time, requiring four operating rooms, to assure that no one backs out once their loved one has received a new kidney.

While paired donation was gaining a foothold in transplant medicine, Dr. Rees heard about an idea he thought might work.

The idea was to come up with an exchange list for people who had willing, but incompatible donors. He found 10 pairs in his own center and sat down with all of their information at his kitchen table. He says he quickly realized that "a computer needs to do this complex matching, not me."

Dr. Rees' father actually designed the first computer model, which has since gone through major changes.

M. Utku Unver, a theoretical economist from Boston College, led the team that redesigned the computer matching system that assigns point values to different characteristics that donors and recipients share. The higher the number, the better the match.

National List Will Make Linking Easier

Donation chains allow for more people to receive transplants and once a match has been made, it is easier than trying to coordinate four simultaneous surgeries, according to Dr. Rees.

From the first donor chain, 10 transplants have been done in four states, including three that were done simultaneously at Johns Hopkins. None of the donors in the chain have reneged on their promise to donate an organ.

Living donations do not always go to the sickest person, as deceased organs do, explains to Dr. Kenneth Andreoni, chairman of the subcommittee for national kidney paired donations at UNOS, the agency that directs the allocation of donated organs.

But he says that NEAD chains can help reduce the time people spend on a waiting list, simply by reducing the list's size.

"The more you can get transplanted, the more access people on the list have to deceased donors. It's really a win-win situation," notes Dr. Andreoni.

But he adds that because of the complexity of managing NEAD chains, it would be better to have a national list of recipient-donor pairs, so that as many pairs as possible can be matched up without having to create a chain.